Developmental partitioning of SYK and ZAP70 prevents autoimmunity and cancer

Sadras, T., Martin, M., Kume, K., Robinson, M. E., Saravanakumar, S., Lenz, G., Chen, Z., Song, J. Y., Siddiqi, T., Oksa, L., Knapp, A. M., Cutler, J., Cosgun, K. N., Klemm, L., Ecker, V., Winchester, J., Ghergus, D., Soulas-Sprauel, P., Kiefer, F., Heisterkamp, N., Pandey, A., Ngo, V., Wang, L., Jumaa, H., Buchner, M., Ruland, J., Chan, W. C., Meffre, E., Martin, T., Muschen, M. (2021). Mol Cell 81, 2094-2111 e2099.

DOI:10.1016/j.molcel.2021.03.043(link is external)


Even though SYK and ZAP70 kinases share high sequence homology and serve analogous functions, their expression in B and T cells is strictly segregated throughout evolution. Here, we identified aberrant ZAP70 expression as a common feature in a broad range of B cell malignancies. We validated SYK as the kinase that sets the thresholds for negative selection of autoreactive and premalignant clones. When aberrantly expressed in B cells, ZAP70 competes with SYK at the BCR signalosome and redirects SYK from negative selection to tonic PI3K signaling, thereby promoting B cell survival. In genetic mouse models for B-ALL and B-CLL, conditional expression of Zap70 accelerated disease onset, while genetic deletion impaired malignant transformation. Inducible activation of Zap70 during B cell development compromised negative selection of autoreactive B cells, resulting in pervasive autoantibody production. Strict segregation of the two kinases is critical for normal B cell selection and represents a central safeguard against the development of autoimmune disease and B cell malignancies.